Ball-caster



(No Model.) 5

. A'. H. MARDEN;

' v IBALL (EASTER.

Patented Mar. 3, 1896.

gar/I1 v u v W/TNEEEEEJ- UNITED STATES PATENT @rmcn.

ALDIS H. MARDEN, OF W'ATERTOYVN, MASSACHUSETTS.

BALL-CASTER.

SPECIFICATION forming part of Letters Patent No. 555,578, dated March 3, 1896. Application filed June 19, 1895. Serial No. 553,336. (No model.)

To aZZ whom it may concern.-

Be it known that I, ALDIs H. MARDEN, a citizen of the United States, residing at W'atertown, in the county of MiddleseX and State of Massachusetts, have invented certain new and useful Improvements in Ball-Casters for Furniture, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which- Figure 1 is a side elevation of a furniturecaster constructed in accordance with myinvention. Fig. 2 is a central vertical section of the same on the line 2 2 of Fig. 1. Fig. 3 is a central vertical section of the same on the line 3 3 of Fig. 2. Fig. 4 is an inverted sectional plan on the line 4 4 of Fig. 2. Fig. 5 is a plan of the yielding bearing-plate of the antifriction cylinder or roller. Fig. 6 is a perspective view of the antifriction-roller detached. Fig. 7 is a central vertical section illustrating a modification of my invention.

My invention relates to that description of casters termed ball-casters, in which the ordinary wheel is replaced by a ball projecting below the shell or casing and rotating in a suitable chamber or socket within the same. To improve casters of this variety and reduce the friction to a minimum is the object of my invention, which consists in certain novel features of construction and combinations of parts, as hereinafter more'particularly set forth and claimed.

In the said drawings, A represents the hollow shell or body of a caster, which is made open at its lower end for the reception of a solid caster-ball B, which projects below the same and is prevented from dropping out, after being inserted within its chamber 1), by contracting the size of the opening through which it is passed by spinning the metal around the edge of said opening in a well-known manner, the ball being free to rotate in all directions, as hereinafter more fully explained. The upper end of theshell A is provided, as usual, with a shank c and a flange cl,

the latter having holes 6 for the reception of the screws by which the caster is attached to a piece of furniture. Between the ball B and a fiat bearing plate or surface f, forming the top of the ball-chamber b, is interposed a single loose antifriction steel cylinder or roller D, against which the ball B bears at asingle point only, as shown in Figs. 2 and 3, while the roller contacts in the direction of its 5 5 length with the flat bearing-surface f only at a single point in its periphery, as shown in Fig. 3, thus reducing the friction to a minimum. The cylinder or roller D not only revolves axially, but also rotates freely in a horizontal plane as the ball B changes its direction of revolution, and to facilitate its rotation in the latter direction and prevent it from cramping or wedging against the sides of the chamber 1) it is provided at each end with a loose antifriction-ball g, which is confined within a chamber h, Fig. 2, in the end of the roller, and is held in place after being inserted therein by spinning the metal around the end of the roller, as previously described for theball B. The balls 9 hear at a single point only against the flat inner ends of their chambers h, and as the roller D is revolved either axially or in ahorizontal plane the contact of the balls with the sides of the chamber b 7 5 reduces the friction to a minimum and enables the ball B to rotate with the slightest movement of the piece of furniture to which the caster is attached.

By the employment of a single loose cylin- 8o der interposed between the caster-ball and a flat bearing-surface thereover, and arranged to revolve both axially and in a horizontal plane, a rolling friction-surface is presented to the ball in all directions, while the latter is in contact with the roller at a single point only, and by providing the ends of the roller with antifriction-balls, as described, the friction is still further reduced at this point, thus enabling the caster-ball to rotate with the greatest possible freedom under all conditions.

In some kinds of chairs, more particularly those used in dining-rooms, it is desirable that the chair should not roll or move around on the floor when occupied, but should be 5 free to be rolled on its casters when not in use. To accomplish this the bearing plate or surface f, on which the antifriction-cylinder D bears, is made to yield in an upward direction against the resistance of a spiral spring it, placed within a chamber m in the upper portion of the shell or body A and exerting a downward pressure against said bearingplate f, which is steadied in its movements by lateral tongues or projections 01, extending outward from its periphery through guideslots (1 in the shell A, as shown in Figs. 1 and 2. The strength of the spring 7c is such that it will offer sufficient resistance to maintain the parts in the position shown in the drawings when the chair is not occupied, thus en abling it to be freely rolled about as desired. \Vhen, however, the chair is occupied, the weight of the occupant will overcome the resistance of the spring and permit the ball B to recede within its chamber 1) until the lower edge 10 of the shell A rests squarely and firmly upon the floor, when the chair will remain in its place as desired. As soon, however, as the chair is relieved of the weight of the occupant the spring 75, bearing on the plate f, will force the caster-ball outward into its normal position, when the chair can be freely moved, as before described.

When the caster is to be applied to tables or other heavy articles of furniture, it is not necessary that the caster-ball should recede within the shell, and I therefore in such case prefer to dispense with the spring and yielding bearing-plate and construct the caster as shown in Fig. 7, which represents it with the antifrietion-cylinder D bearing directly against the solid unyielding fiat top f of the caster-ball chamber 1), the operation of the caster-ball and antifriction-roller being in such case preciselythe same as in the construction first described, except that the ball cannot recede from its normal operative position.

I am aware that a series of antifriction-rollers have been interposed triangularly between a caster-ball and a bearing-plate thereover; but these rollers have been placed Within eylindrical bearings or grooves in said bearingplate, which produced much friction, as they covered nearly one-half of thecircumference of the rollers, whereas my single loose roller touches the fiat surface of the bearing-plate only at a single point in its periphery, and, furthermore, is capable of rotating in a horizontal plane as well as axially, whereby a great reduction in friction is accomplished I do not therefore claim, broadly, a roller or cylinder placed between a caster-ball and a bearing-plate arranged above the same.

I am also aware that a spring has been employed to enable the caster-ball to partially recede within its casing and thereby adjust itself to the irregularities of the floor, but in such casters the ball could not recede sufficiently far to enable the shell or casing to rest upon the floor, as is the ease in my caster. Hence I make no broad claim to the employment of a spring in connection with a receding caster-ball.

lVhat I claim as my invention, and desire to secure by Letters Patent, is-

1. In aball-caster, the combination with the shell or easing provided with a chamber open at its bottom, and a ball rotating within said chamber and projecting from the open end thereof, of a single loose antifriction roller or cylinder interposed between the top of the caster-ball and a flat bearing-surface forming the top of the ball-chamber, said antifrictionroller being adapted to rotate both axially and in a horizontal plane, and being provided at its opposite ends with loose antifriction-balls projecting therefrom and adapted to contact with the sides or walls of the caster-ball chamber, substantially as and for the purpose described.

2. In a ball-caster, the combination with the shell or casing provided with a chamber open at its bottom, and a ball rotating within said chamber and projecting from the open end thereof, of a vertically-movable disk or bearing-plate located above the caster-ball and provided with lateral tongues or projections fitting within vertical guide-slots in the shell or casing, a single loose antifriction roller or cylinder interposed between the top of the caster-ball and the bearing-plate and adapted to rotate both axially and in a horizontal plane, and a spring located above the bearing-plate and exerting a downward pressure thereon, said spring serving to maintain the caster-ball normally in an operative position, but permitting it to recede far enough to allow the shell or casing to rest on the floor when sufficient weight is put upon the caster to overcome the resistance of the spring, substantially as set forth.

In a ball-caster, the combination with the shell or casing A, provided with a chamber open at its bottom and having vertical guideslots q, of the caster-ball B, rotating within said chamber, the vertically-movable disk or bearing-plate f, located above the caster-ball and provided with lateral tongues 2, projecting from its periphery and fitting within the guide-slots q, the loose antifriction-roller I), interposed between the top of the ball 13, and the yielding bearing-plate f, said roller being adapted to rotate both axially and in a horizontal plane, and being provided at its opposite ends with loose antifriction-balls g, adapted to contact with the sides or walls of the caster-ball chamber, and the spring 7c, located above the plate f, and exerting a downward pressure thereon to keep the ball B, normally in an operative position, said ball being adapted to recede within its chamber far enough to permit the shell A, to rest on the floor when a downward pressure is exerted upon the caster sufficient to overcoinethe resistance of the spring 7t, all constructed to operate substantially as described.

Witness my hand this 18th day of June, A. D. 1895.

ALDIS II. MARDEN.

In presence of- P. E. TESCHEMACHER, GEO. A. YEo. 

